1. Field of the Invention
This invention relates to an improved medical positioning device for the precise positioning of a medical treatment instrument into an interior organ. The invention additionally contemplates a related method of using the present invention. The present medical positioning device penetrates selected tissue to precisely position a medical treatment instrument into an interior organ while minimizing trauma to tissue surrounding the treatment site. By minimizing trauma to surrounding tissue, the medical positioning device allows for greater medical benefits while minimizing side effects. This invention is particularly useful for guiding and positioning a catheter or an electrical stimulation lead into the brain along a non-linear insertion path.
2. Description of the Related Art
In many medical procedures, it is necessary to position a catheter or an electrical stimulation lead at a precise location within a patient's body. Often, precise placement of a medical treatment instrument is difficult because of the location of the treatment site in the body. These difficult treatment sites may be nearby critical body organs, nerves, or other components that are at high risk of being damaged while the instrument is moved to the treatment site.
The placement of catheters and leads into the body, and particularly into the brain, has been primarily in a straight, linear manner. To place the catheter or lead straight into the brain, a straight, solid metal wire, called a stylet, is used. For many potential treatment sites, a straight insertion of a catheter using a wire stylet has drawbacks that prevent the optimal placement of a medical treatment instrument. For example, the straight insertion of an instrument into some portions of the brain would pass through other critical brain areas, which control a patient's sensory or bodily functions, thereby possibly causing damage to a patient's speech, hearing, or sight. For other portions of the brain, a linear insertion route would require insertion through other undesirable locations that would cause increased trauma to the patient. Ideally, a surgeon wishes to guide a catheter or lead into the brain while avoiding these critical brain areas. To avoid these critical brain areas, it has been found to be desirable to insert the medical treatment instrument into the brain along a curved or nonlinear path, so as to allow a surgeon to precisely place a catheter or stimulation lead into the brain on an insertion path that avoids damage to critical brain tissue.
A number of prior art positioning devices exist that allow for the non-linear placement of a catheter or lead into the body. For example, U.S. Pat. No. 5,195,968 to Lundquist shows a catheter steering mechanism utilizing a pull wire type guiding system. Pull wire type guiding systems have been used primarily to place a catheter into the heart by way of coronary veins. Also, U.S. Pat. No. 4,873,983 to Winters, U.S. Pat. No. 4,917,102 to Miller et al, and U.S. Pat. No. 5,308,324 to Hammerslag et al, show flexible movable core guide wires. Flexible movable core guide wires have been primarily used to insert a catheter through the coronary arteries.
The placement of medical treatment instruments into interior organs presents an additional challenge that makes prior art positioning devices less suitable for use in solid, soft tissue interior organs, such as the brain. Known prior art devices have been used primarily in open cavities that are hollow or filled only with a liquid such as blood. Because open cavities are essentially hollow, a surgeon may move a medical positioning device from side to side within the hollow cavity without damaging tissue by the device's side to side movement. In a solid interior organ, like the brain, however, side to side movement would cause sensitive tissue to be damaged or even sliced.
If a surgeon used a pull wire guiding system or a movable core guide wire system to insert a catheter or lead into the brain, it would damage or slice brain tissue. Additionally, movable core guide wires may be excessively flexible and not strong enough to be effectively used for inserting a treatment instrument into and through brain tissue. Because of these drawbacks, surgeons have typically not used pull wire guiding systems or movable core guide wire systems for placing medical treatment instruments into the brain. Instead, brain surgeons have generally used straight stylets for the straight, linear insertion of a medical treatment device into the brain. Thus, there is a need for a medical positioning device that will allow for the precise placement of medical treatment devices into soft tissue interior organs along a curved path with minimal or non-existent, critical lateral or slicing movement.
The present invention is an improved medical positioning device which allows the user to precisely position a catheter or lead into the brain following a non-linear or curved insertion path while minimizing or even eliminating unwanted damage to surrounding brain tissue and trauma to a patient.